Dielectric reflector for electric waves

ABSTRACT

A weatherproof dielectric reflector for electric waves having a spherical dielectric lens, an annular electric wave reflector of predetermined width disposed on the spherical surface of the spherical dielectric lens at a position about a horizontal plane passing the central point of the spherical dielectric lens or a point vertically spaced apart from the central point of the spherical dielectric lens, a dish-shaped electric wave reflector of predetermined area disposed on the spherical surface of the spherical dielectric lens at a position about a vertical line passing the central point of the spherical dielectric lens and extending downwardly thereof, a covering for the reflectors and lens, and a support therefor.

United States Patent [191 Ota et a1.

1 1 Jan. 14, 1975 DIELECTRIC REFLECTOR FOR ELECTRIC WAVES [75] Inventors: Hiroshi Ota, Tokyo; Kazumi Mizutani, Kanagawa-ken, both of Japan [73] Assignee: Kabushikikaisha Tokyo Keiki,

Tokyo, Japan [22] Filed: July 11, 1973 [21] Appl. No.: 378,376

[30] Foreign Application Priority Data Horst 343/18 11 Bradford 343/18 B [57] ABSTRACT A weatherproof dielectric reflector for electric waves having a spherical dielectric lens, an annular electric wave reflector of predetermined width disposed on the spherical surface of the spherical dielectric lens at a position about a horizontal plane passing the central point of the spherical dielectric lens or a point vertically spaced apart from the central point of the spherical dielectric lens, a dish-shaped electric wave reflector of predetermined area disposed on the spherical surface of the spherical dielectric lens at a position about a vertical line passing the central point of the spherical dielectric lens and extending downwardly thereof, a covering for the reflectors and lens, and a support therefor.

4 Claims, 2 Drawing Figures DIELECTRIC REFLECTOR FOR ELECTRIC WAVES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a dielectric reflector for electric waves employing a spherical dielectric lens, and more particularly to a dielectric reflector for electric waves adapted for use with, for example, a lifesaving outfit to ensure that, in the case of a disaster at sea, accurate positions of survivors using the life-saving outfit can readily be found by radar on search ships and search planes.

2. Description of the Prior Art Hitherto, various life preservers for a disaster at sea such as life jackets, life buoys, life boats, life rafts and the like have been employed but there has not yet been proposed a life-saving outfit which allows ease in finding accurate positions of survivors by using electric waves. Therefore, it has been desired to realize a novel electric wave reflector which can be used with life preservers such mentioned above and which facilitates a search for survivors holding on to the life preservers by radar on search ships and search planes.

SUMMARY OF THE INVENTION Accordingly, this invention is to provide a novel dielectric reflector for electric waves which can be used with a life-saving outfit and facilitates finding accurate positions of survivors at sea by radar on search ships and search planes.

In accordance with the present invention, the weatherproof dielectric reflector has sufficiently large reflection factor and radar cross section and exhibits omnidirectional characteristics in a horizontal plane and upward reflection characteristic. Consequently, the use of the dielectric reflector with the life-saving outfit ensures to facilitate a search for survivors by search ships and planes equipped with radar.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are schematic front views illustrating examples of a dielectric reflector of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates one example of the dielectric reflector for electric waves according to this invention, which comprises a spherical dielectric lens 1 of known Luneberg lens construction, an annular electric wave reflector 2 wrapped around it and a dish-shaped electric wave reflector 3 mounted on the lens 1. The annular electric wave reflector 2 is disposed on the spherical surface of the dielectric lens 1 at a position about a horizontal plane passing the central point of the lens 1 and has a width in a vertical direction expressed by a predetermined central angle 0 to the central point 0. The dish-shaped electric wave reflector 3 is mounted on the spherical surface of the lens 1 at a position about a vertical line passing the central point 0 and extending downwardly thereof and has an area expressed by a predetermined central cubic angle (1) to the central point 0. In this case, the electric wave reflectors 2 and 3 may be made ofa conductive plate material or a conductive foil material. It is preferred to cover both of the electric reflectors 2 and 3 with a thin protective film 4 of an electric wave transparent material as indicated by a chain line in the figure. Further, it is preferred to provide a support 5 by appropriate means at a position, for example, corresponding to the electric wave reflector 3 for the attachment of the dielectric reflector to a life preserver, for example, a life boat.

With such a construction, radar waves, which arrive at the dielectric reflector along a horizontal plane, in the figure, from the left-hand side, as indicated by the arrow A, enter the dielectric lens I at a position, not covered by the electric wave reflector 2, and are focused by the lens I to a point on its right-hand surface in the figure. By the way, since the reflector 2 is present at the focused position, the radar wave thus focused is reflected at the position of the reflector 2 back to the left in the figure and out from the lens 1. Thus, a re flected radar wave is obtained based on the horizontal incident radar wave. In this case, since the annular electric wave reflector 2 is wrapped around the dielectric lens 1 at a position about a horizontal plane passing the central point 0, even if radar waves enter the dielectric lens 1 in any direction in a horizontal plane, the reflected radar wave can be obtained from the dielectric reflector. Therefore, the dielectric reflector has omnidirectional reflection characteristics in a horizontal plane. Further, radar waves striking the dielectric reflector from above as indicated by the arrow B is similarly focused in the lens 1 to a point on its lower surface and reflected back upwardly by the electric wave reflector 3.

Accordingly, the dielectric reflector of this invention has omnidirectional reflection characteristics in a horizontal plane and upward reflection characteristic. In this case, if the width of the reflector 2 and the area of the reflector 3 are appropriately selected, reflection characteristics in all directions except downward one can be obtained. Further, the dielectric reflector employs the dielectric lens, and hence has large reflection factor and radar cross section. Consequently, the provision of the dielectric reflector of this invention in the life-saving outfit for a disaster at sea ensures to facilitate a search by search ships or planes equipped with radar. This is especially true in the case where the dielectric lens 1 is of the Luneberg lens construction as described above. Further, since the dielectric lens I can be made of a dielectric material of relatively small specific density such as polystyrene or the like, the dielectric reflector of this invention is light as a whole. Accordingly, when the dielectric reflector is assembled with the life-saving outfit, it is not necessary to take its buoyancy into consideration.

In the foregoing, the electric wave reflector 2 has been described to be disposed on the dielectric lens 1 at the position about the horizontal plane passing the central point 0 but the dielectric reflector may be of such a construction as depicted in FIG. 2 which is identical with that of FIG. 1 except that the electric wave reflector 2 is disposed at a position about a horizontal plane passing a point 0' a little apart from the central point 0 in a vertical direction. With such a construction, even if the dielectric reflector is slightly tilted as a while, it provides the same effects as those obtainable with the reflector of FIG. 1.

Although this invention has been described in connection with the case where the dielectric lens has the Luneberg lens construction (the dielectric constant varies in its radial direction), the invention is also applicable to the case where the dielectric lens is of the type having a constant dielectric constant in the radial direction.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

We claim as our invention:

1. A dielectric reflector for electric waves for use with a life-saving outfit comprising a spherical dielectric lens, an annular electric wave reflector having a predetermined width and disposed on the spherical surface of the spherical dielectric lens at a position about a horizontal plane passing the central point of the spherical dielectric lens, a dish-shaped electric wave reflector having a predetermined area and disposed on the spherical surface of the spherical dielectric lens at a position about a vertical line passing through the central point of the spherical dielectric lens and extending downwardly thereof, a protective film of an electric wave transparent material covering the spherical dielectric lens together with the annular electric wave reflector and the dish-shaped electric wave reflector, and a support extending downwardly from the position of the dish-shaped electric wave reflector.

2. A dielectric reflector for electric waves for use with a life-saving outfit comprising a spherical dielectric lens, an annular electric wave reflector having a predetermined width and disposed on the spherical surface of the spherical dielectric lens at a position about a horizontal plane passing a point vertically spaced apart from the central point of the spherical dielectric lens, a dish-shaped electric wave reflector having a predetermined area and disposed on the spherical surface of the spherical dielectric lens at a position about a vertical line passing through the central point of the spherical dielectric lens and extending downwardly thereof, a protective film of an electric wave transparent material covering the spherical dielectric lens together with the annular electric wave reflector and the dish-shaped electric wave reflector, and a support extending downwardly from the position of the dish-shaped electric wave reflector.

3. A dielectric reflector for electric waves according to claim 1, wherein the spherical dielectric lens has a Luneberg lens construction.

4. A dielectric reflector for electric waves according to claim 2, wherein the spherical dielectric lens has a Luneberg lens construction. 

1. A dielectric reflector for electric waves for use with a life-saving outfit comprising a spherical dielectric lens, an annular electric wave reflector having a predetermined width and disposed on the spherical surface of the spherical dielectric lens at a position about a horizontal plane passing the central point of the spherical dielectric lens, a dish-shaped electric wave reflector having a predetermined area and disposed on the spherical surface of the spherical dielectric lens at a position about a vertical line passing through the central point of the spherical dielectric lens and extending downwardly thereof, a protective film of an electric wave transparent material covering the spherical dielectric lens together with the annular electric wave reflector and the dish-shaped electric wave reflector, and a support extending downwardly from the position of the dish-shaped electric wave reflector.
 2. A dielectric reflector for electric waves for use with a life-saving outfit comprising a spherical dielectric lens, an annular electric wave reflector having a predetermined width and disposed on the spherical surface of the spherical dielectric lens at a position about a horizontal plane passing a point vertically spaced apart from the central point of the spherical dielectric lens, a dish-shaped electric wave reflector having a predetermined area and disposed on the spherical surface of the spherical dielectric lens at a position about a vertical line passing through the central point of the spherical dielectric lens and extending downwardly thereof, a protective film of an electric wave transparent material covering the spherical dielectric lens together with the annular electric wave reflector and the dish-shaped electric wave reflector, and a support extending downwardly from the position of the dish-shaped electric wave reflector.
 3. A dielectric reflector for electric waves according to claim 1, wherein the spherical dielectric lens has a Luneberg lens construction.
 4. A dielectric reflector for electric waves according to claim 2, wherein the spherical dielectric lens has a Luneberg lens construction. 